CFB锅炉尾部喷氨深度脱硫气液两相流动特性研究

发布时间：2018-09-17 15:16

【摘要】：循环流化床(CFB)锅炉以其低污染物排放、较强的煤种适应性和灰渣可综合利用等优点受到业内的广泛推崇。但随着国家对火电厂污染物排放标准的不断提高,循环流换床锅炉仅靠燃烧中投放石灰石脱硫已不能达到国家新的火电厂SO2污染物排放标准,因此,在炉内石灰石脱硫的基础上采用锅炉尾部加装深度烟气脱硫装置是其发展方向之一。本文以山西某300MW机组CFB煤矸石电厂结合自身实际设计的炉内石灰石脱硫+尾部烟气喷氨增湿活化脱硫的联合深度脱硫系统为研究对象,对该装置内喷嘴性能和反应段气液两相流动特性进行研究。本文首先对脱硫装置中的关键设备——雾化喷嘴的雾化特性进行实验研究,利用高速动态摄像仪测量液滴粒径,得到不同流体压力下,压力与流体流量、雾化角、射程、扇形流量分布之间的关系。其次,在某300MW机组CFB煤矸石锅炉的尾部烟道加装喷氨深度脱硫装置,并在该锅炉上开展现场深度脱硫试验研究。通过改变炉内投石灰石量、喷氨量、氨水浓度和喷嘴个数,观察喷入脱硫剂氨水前后烟道中SO2浓度和飞灰中CaO含量的变化。试验结果表明:在炉内投运石灰石脱硫基础上,在尾部脱硫剂喷入烟道后,烟气中的SO2浓度会进一步明显降低,飞灰中CaO的含量减少。现场试验结果验证了此方法的可行性,脱硫效果明显,具有较好的推广价值。最后,以该尾部喷氨深度脱硫装置为研究对象,建立气液两相流动的三维数学模型,采用计算流体力学软件Fluent对脱硫剂喷入烟道后的气液两相流场进行数值模拟,计算得到烟气流场、脱硫剂喷入烟道后在流场中的轨迹图和烟道截面处的浓度分布图。在此基础上,对喷嘴位置和喷射角度对气相流场的影响进行优化计算,确定喷嘴流量变化时脱硫剂与烟气混合的最佳方案,计算结果与试验数据吻合较好。研究结果为同类型CFB锅炉的深度脱硫技术研发提供参考依据。
[Abstract]:Circulating fluidized bed (CFB) boiler is widely praised by the industry for its advantages of low pollutant emission, strong coal adaptability and comprehensive utilization of ash and slag. However, with the continuous improvement of the national emission standards for pollutants in thermal power plants, the circulating flow boiler can not meet the new SO2 emission standard of thermal power plants only by adding limestone desulfurization in combustion. On the basis of limestone desulphurization in furnace, it is one of the developing directions to adopt boiler tail with deep flue gas desulphurization device. In this paper, the combined deep desulphurization system of limestone desulphurization tail gas by ammonia humidification and activation desulfurization is designed by CFB gangue power plant of a certain 300MW unit in Shanxi province combined with its own actual design. The nozzle performance and gas-liquid two-phase flow characteristics in the reactor were studied. In this paper, the atomization characteristics of atomizing nozzle, the key equipment in desulfurization device, are studied experimentally. The droplet size is measured by high speed dynamic camera, and the pressure and fluid flow rate, atomization angle and range are obtained under different fluid pressure. The relationship between the fan flow distribution. Secondly, an ammonia injection deep desulfurization device is added to the tail flue of a CFB gangue boiler of a 300MW unit, and the field deep desulfurization test is carried out on the boiler. By changing the quantity of limestone, ammonia, ammonia and the number of nozzles, the changes of SO2 concentration in flue and CaO content in fly ash were observed before and after injection of ammonia water. The results show that on the basis of limestone desulphurization in furnace, the concentration of SO2 in flue gas will further decrease and the content of CaO in fly ash will decrease after the tail desulfurizer is injected into flue gas. The results of field test proved the feasibility of this method, the desulfurization effect is obvious, and it is worth popularizing. Finally, a three-dimensional mathematical model of gas-liquid two-phase flow is established, and a numerical simulation of gas-liquid two-phase flow field after desulphurizer injection into flue is carried out by using computational fluid dynamics software Fluent. The flow field of flue gas, the trace diagram of flue gas flow field and the concentration distribution at the section of flue were obtained after the desulphurizer was injected into the flue. On this basis, the influence of nozzle position and injection angle on gas flow field is optimized, and the optimum scheme of desulfurizing agent and flue gas mixing when nozzle flow rate changes is determined. The calculated results are in good agreement with experimental data. The results provide a reference for the development of deep desulfurization technology for the same type of CFB boilers.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TK229.66

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